The present invention relates to an electronic key apparatus which comprises a memory for storing an encrypted or secret code for releasing a lock, and which supplies an encrypted code stored in the memory, by means of radio wave, light, ultrasonic wave, or the like, to release a lock.
A conventional security apparatus for a gate or door of a house or room, a door of a vehicle, a door or lid of a safe, desk, locker, drawer, or the like comprises a lock mechanism consisting of a mechanical lock and a key. The lock mechanism can be released only when a combination of mechanical factors, such as a three-dimensional shape in the lock, or the length or position or presence/absence of a pin or cylinder, coincides mechanically or dynamically with the three-dimensional shape, length, or position of the key or the presence/absence thereof.
In recent years, an electronically controlled lock apparatus has been developed in place of the mechanical lock mechanism using the mechanical lock and the key. In such a lock mechanism, for example, the lock has a plurality of numerical buttons, and electronic information "1" or "0" is input, by means of an electric signal (e.g., a high or low voltage level, or a large or small current, or an ON/OFF pulse) upon depression of buttons corresponding to a predetermined number, thereby locking/unlocking the lock mechanism, without using a mechanical key. In addition, an apparatus which can lock/unlock the lock mechanism from a distant location, by remote control, using a radio wave, or an apparatus utilizing a magnetic strip card on which an encrypted code is recorded on magnetic tape, is known.
U.S. Pat. No. 4,573,046 describes an electronic locking system which comprises a wristwatch which has a memory for storing a code for releasing a lock, and which radiates the code to the lock by way of an optical means, and also describes an apparatus for releasing the lock, in response to a predetermined code.
In the above system using mechanical comparison means, a key can be easily duplicated or counterfeited. Since the respective locks require different keys, the user must carry around a large number of keys. In addition, each lock must be manually locked/unlocked, thus posing problems in terms of operation, use, or security. When the lock is to be replaced, the keys must also be replaced. Accordingly, it is difficult to perform centralized control, resulting therefore, in poor compatibility or systematization.
In an electronically controlled apparatus comprising numerical buttons, the number to be input, in respect of each lock, must be memorized. If there are a plurality of locks, the user may easily forget their numbers. In the apparatus utilizing remote control, a remote control unit must be prepared for each lock, and the user must bring them with him. There is always the risk that the user may lose one or more the remote control units. In the apparatus using the magnetic strip card, the user must carry around a large number of cards corresponding to the respective locks, and he may easily lose these cards.
In the system disclosed in U.S. Pat. No. 4,573,046, a plurality of codes corresponding to a plurality of locks can be stored, and the code corresponding to a desired lock can be selectively output upon switch operation, thus resulting in increased convenience.
However, in the system of this patent, if a wristwatch storing the codes of the locks is stolen, all the locks may be unlocked by the signal emitted from the stolen wristwatch. Even if the watch was not stolen, there is always the possibility that, a third party may operate the switches without permission, to erase or update the codes, with the result that the locks cannot then be unlocked by the original user.